A tire-vulcanizing mold is usually used for the manufacture of tires, which mold is built of several profiled segments. In order to be able to place the tire into the mold or remove same from the mold after the vulcanizing operation, the individual profiled segments can be moved relative to one another. Vulcanizing molds are known in which a division into individual profiled segments is done relative to the center of the tire, however, the vulcanizing mold can also be divided in radial direction into individual profiled segments. Such a tire-vulcanizing mold is known, for example, from DE-OS 3631533.
It is necessary, during the manufacture of a tire, to remove the gases existing in the tire-vulcanizing mold during the forming of the tire blank. The difficulty, in contrast to common molds, is that the tire, in particular the tread surface, is designed to have many profiles so that the tire-vulcanizing mold is divided into individual chambers by the barriers and ribs needed for the manufacture of such grooves and slots. Thus, gases collect in the respective chambers during the forming process and must be discharged from each one of these chambers.
It is known from the state of the art to solve this venting problem in such a manner that the profiled segments are equipped with individual bores. The gases can be removed through the bores, however, the rubber mixture also enters at the same time the bore and flows at least partly through the bore so that peg-like projections exist on the finished product, which peg-like projections are formed by the material in the bores. Thus, the finished tires must be finish-worked in order to remove these projections or rubber nipples. This requires an additional manufacturing expense. Also these projections or nipples create additional waste, which should be avoided.